A tomato-and-onion omelette, washed down with hot coffee: that was the last breakfast of U.S. Ambassador Chris Stevens’ life. And although the scene in the U.S. consulate’s canteen in Benghazi on Tuesday morning looked serene, under the surface there were signs of potential trouble, according to the Libyan politician who had breakfast with Stevens the morning before the ambassador and three other Americans died in a violent assault by armed Islamic militants. “I told him the security was not enough,” Fathi Baja, a political-science professor and one of the leaders of Libya’s rebel government during last year’s revolution, told TIME on Thursday. “I said, ‘Chris, this is a U.S. consulate. You have to add to the number of people, bring Americans here to guard it because the Libyans are not trained.”

Stevens, says Baja, listened attentively — but it was too late. On Tuesday night, armed Islamic militants laid siege to the consulate, firing rockets and grenades into the main building and the annex, pinning the staff and its security detail inside the blazing complex; U.S. officials told reporters on Wednesday they believed it took Libyan security guards about four hours to regain control of the main building. In the chaos, Stevens was separated in the dark from his colleagues, and hours later was transported by Libyans to a Benghazi hospital, where he died, alone, apparently of asphyxiation from the smoke.

U.S. officials told reporters on Wednesday that the Benghazi consulate had “a robust American security presence, including a strong component of regional security officers.” And indeed, one of the four Americans killed was former Navy SEAL Glen Doherty, who was “on security detail” and “protecting the ambassador,” his sister Katie Quigly told the Boston Globe. Also killed was an information-management officer, Sean Smith. The fourth American who died has not yet been identified. Yet Baja describes a very different picture from his visit on Tuesday morning, even remarking at how relaxed the scene was when he returned to the consulate building a short while after leaving Stevens, in order to collect the mobile phone he had accidentally left behind. “The consulate was very calm, with video [surveillance] cameras outside,” Baja says. “But inside there were only four security guards, all Libyans — four! — and with only Kalashnikovs on their backs. I said, ‘Chris, this is the most powerful country in the world. Other countries all have more guards than the U.S.,'” he says, naming as two examples Jordan and Morocco.

With the compound now an evacuated, smoldering ruin, Baja, who befriended Stevens in Benghazi during last year’s seven-month civil war, and in recent weeks had shared long Ramadan dinners with him, says he felt stricken not only by the loss but also by the sense that perhaps the tragedy could have been averted, had there been tighter security on the ground, and — more especially — had Libya’s nascent government cracked down against armed militia groups. Bristling with weaponry, much of it from Muammar Gaddafi’s huge abandoned arsenals, groups of former fighters have been permitted to act as local security forces in towns across Libya during the postwar upheaval in order to fill the security vacuum, despite the scant loyalty among many of them to the new democracy. “Up to now, there has been cover from the government for these extremist people,” Baja says, adding that he and Stevens had discussed for months the urgent threats from armed militia. “[Government officials] still pay them salaries, and I think this is disgusting.”

President Obama vowed on Wednesday to help track down the attackers. U.S. officials suspect the attack was a planned operation, rather than the result of a demonstration that got out of control. In an opinion piece on CNN.com on Thursday, Noman Benotman, a former leader of the militant Libyan Islamic Fighting Group who now runs the Quilliam Foundation, an anti-extremist organization in London, said he believed the attack had been the work of 20 militants. He told CNN that he believed a militant group called the Omar Abdul Rahman Brigades could have coordinated the attack, perhaps to avenge the killing of Abu Yahya al-Libi, a Libyan al-Qaeda leader, who died in a U.S. drone strike in Pakistan last June; the group also claimed responsibility for the attack last May against the International Red Cross in Benghazi.

In the scramble to figure out what went so calamitously wrong, U.S. officials deployed 50 Marines to Tripoli from a base in Spain, as members of an elite antiterrorism force called FAST, according to the Associated Press, citing unnamed U.S. officials. In addition, two American warships have been stationed off the Libyan coast.

Ironically, Benghazi had ostensibly held a special bond, as well as a debt of gratitude, to the U.S. and other Western countries — something highlighted in the bitter comments by Secretary of State Hillary Clinton on Wednesday, when she expressed dismay that the attack occurred in a city the U.S. helped to save. French and American military jets pounded Gaddafi’s forces outside the city in March last year, saving Benghazi from the threat of mass slaughter.

The deep fondness for the U.S. is indeed felt in Benghazi, according to Baja, who was head of the political-affairs committee for Libya’s National Transitional Council until the elected government was installed last month. Stevens and Baja had met on Tuesday morning primarily to plan the American Cultural Center’s official opening, which was scheduled for Wednesday evening. “There was going to be a big ceremony,” Baja says. “There was going to be English classes. It was a very nice place.”

Recalling what he told Stevens over their omelettes, Baja says, “I told him, people admire the U.S. style of life, but that there were extremists, and we have to work in a cooperative way to put an end to these people,” adding that he had advocated pushing Libyan officials to crack down on armed militia. “He agreed with that. He knew this, he knew the names of the militia I told him, and their background.” Now that knowledge — some of it gone with Stevens’ disastrous death — could become key details in the grim investigation.